body {
    margin: 0;
    background-color: gray;
    font-family: Arial, Helvetica, sans-serif;
}

.container {
    max-width: 700px;
    width: 80%;
    min-width: 400px;
    margin: 0 auto;
    background-color: skyblue;
    padding: 20px;
}

h1 {
    text-align: center;
}

label {
    display: block;
    margin-bottom: 5px;
    font-size: 1.2rem;
}

input,
select,
textarea {
    width: 100%;
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.radio-group {
    display: flex;
    font-size: 1rem;
    align-items: center;
}

.radio-group input[type="radio"] {
    display: inline-block;
    width: 10%;
}


input:focus,
textarea:focus {
    border: 1px solid black;
    outline: auto blue;
}

input:valid,
select:valid,
textarea:valid {
    border: 1px solid green;
}

input:invalid,
select:invalid,
textarea:invalid {
    border: 1px solid red;
}

button:hover {
    background-color: green;
}

.radio-group input[type="radio"]:checked {
    border-color: red;
    background-color: green;
    box-shadow: inset 0 0 0 2px red;
}

input[type="radio"]:checked+label {
    color: green;
}

input:first-of-type {
    border-radius: 5px;
}